The microbial flora of herring fillets after storage in carbon dioxide, nitrogen or air at 2 degrees C

Herring fillets from the Baltic Sea were stored in glass vessels in air, nitrogen or carbon dioxide (CO2) at 2 degrees C and the microbial development was studied. The microbiological shelf-life of the herring (the time to reach 10(7) organisms/g) was prolonged by a factor of 3.5 in CO2 as compared to air. The corresponding factor in nitrogen was 1.5. The microflora of fresh and spoiled herring was classified. The initial microflora was dominated by coryneforms, Flavobacterium spp., Moraxella-like organisms and Pseudomonas spp. The spoilage-flora in air (after 9 d) was dominated by Pseudomonas spp. and Moraxella-like organisms, and in nitrogen (14 d) Enterobacteriaceae, Vibrionaceae and Lactobacillus spp. were dominant. Homofermentative Lactobacillus spp. were the only organisms isolated from fillets stored in CO2 (28 d). It was concluded that storing fresh fish in pure CO2 at low refrigeration temperatures is a method with industrial potential. The method (1) improves the microbiological stability and (2) reduces the microbiological health hazards of the fish.